Today, we are going to talk about one of the essential amino acids: Histidine or L-Histidine. Above all, we will focus on its properties for our health and the performance.
What is Histidine?
In short, histidine is a one of the 22 proteinogenic amino acids that make up our genetic code and which are used for the protein synthesis. Moreover, it is also one of the 9 essential amino acids that we have to obtain from the diet in order to prevent the protein breakdown and malnourishment.
In nature, we can find the histidine levorotatory enantiomer, in other words, L-histidine.
It is an amino acid that is present in many foods, both from animals and vegetables. Therefore, a deficiency is a strange condition that is usually related to genetic alterations or severe malnourishment.
In general, this is the amount of L-histidine available in some of the most common products of a western diet:
Chart I. Food sources of L-histidine (Tessari et al., 2016).
What are its functions?
L-histidine is a essential amino acid, as such, we need to obtain it from external sources in order to synthesize proteins.
In addition, L-histidine is the precursor of the synthesis of other biological compounds. For instance, histamine (immune modulator) and carnosine (powerful endogenous antioxidant).
In fact, histidine itself is involved in the catalysis of a wide range of reactions:
- The methylation of arginine residues.
- The synthesis of urocanic acid.
- Also a precursor of the synthesis of glutamic acid.
- Which protects the skin from the ultraviolet radiation and regulates the immune response.
- And the biosynthesis of other genomic and non-genomic intermediary organic compounds.
Importance of Histidine
Synthesis of Histamine
The importance of L-histidine was clearly determined after establishing a direct and indispensable connection to the histamine synthesis. This is an amine that is released by specific types of white cells in order to stop an antigen (strange agent that enters our body).
Consequently, this can trigger the classic “allergic reaction” that involves skin rashes, edema, bronchoconstriction, mucous secretion, watery eyes, coughing…
All these symptoms are quite unpleasant but necessary in order to protect us from an external agent. In fact, they improve the orientation and binding of the leukocytes to the antigens, while controlling the inflammatory molecules. All in all, it improves the protective response of the immune system.
Histamine and histidine play a crucial role in protecting the organism, specially when it comes to the myelin sheaths. These elements cover the neuron axons and they help to prevent the onset of neurodegenerative diseases (such as Parkinson, Huntington or Multiple Sclerosis).
Figure I. Effects of histamine in the organism.
We need histamine to stimulate the proton production in the stomach parietal cells. Consequently, we will stimulate the production of chlorhydric acid as well as the required acid environment necessary for the stomach.
Figure II. Mechanism of the acid secretion in the stomach. (Bowsen, s.f.).
Histamine and its mechanisms are regulated by the activation of the H2 receptors of the stomach. In fact, they are necessary if we want to digest food properly and not suffer hypochlorhydria, which tends to cause malnourishment and digestive disorders.
Moreover, it increases the blood bicarbonate levels, our main extracellular buffer mechanism that keeps the pH stable when when facing problems in the acid-base balance.
Figure III. Acid-base scale. Retrieved from http://med.se-todo.com/himiya/14326/index.html.
L-histidine is an amphoteric amino acid. In other words, it has the ability to balance the pH working as an acid or base depending on the situation.
Perhaps you did not know this properties, but you have probably heard about carnosine. This dipeptide is made up of L-histidine and Beta-Alanine, which works as an intracellular buffer. In fact, it controls the pH of the muscle tissue, protecting us from acidosis and letting us do high intensity exercise without affecting the muscle function.
Well, these effects of carnosine are due to the presence of the imidazole ring from histidine.
Figure IV. Buffer mechanism of the imidazole buffer in the side chain of carnosine). (Lancha Junior et a., 2015).
That is why L-histidine has been related to the ability to buffer the inflammatory response associated with several diseases and stress caused by physical exercise.
Moreover, it is currently being studied due to its potential benefits for improving rheumatoid arthritis. In addition, it has promising results when it comes to improving the symptoms of rigidity and impaired movement of these patients (Pinals et al., 1977).
In general, the daily requirements of L-histidine in adults are of 10mg/kg/day according to the FAO (1992).
As you can see in the previous chart with the food sources of L-histidine, 100g of beef or 200g of quinoa are enough to meet the requirements. These limits were determined for situations of extreme poverty and malnourishment. In fact, a deficiency in Western countries is extremely rare.
Do not forget that if you are an athlete, you protein requirements will be higher. So, if we take into account that the minimum protein requirements are 0.66g/kg/day, and you take at least 1.2kg/kg/day (depending on the intensity of the activity)… this means that your histidine requirements will be twice as much.
- Bowsen, R. (s.f.). The Parietal Cell: Mechanism of Acid Secretion.
- Kessler, A., & Raja, A. (2019, 9 octubre). Biochemistry, Histidine. StatPearls – NCBI Bookshelf.
- Lancha Junior, A. H., de Salles Painelli, V., Saunders, B., & Artioli, G. G. (2015). Nutritional Strategies to Modulate Intracellular and Extracellular Buffering Capacity During High-Intensity Exercise. Sports Medicine, 45, 71–81.
- Pinals, R. S., Harris, E. D., Burnett, J. B., & Gerber, D. A. (1977). Treatment of rheumatoid arthritis with L-histidine: a randomized, placebo-controlled, double-blind trial. Journal of Rheumatology, 4(4), 414–419.
- PubChem (s.f.). Histidine.
- Tessari, P., Lante, A., & Mosca, G. (2016). Essential amino acids: Master regulators of nutrition and environmental footprint? Scientific Reports, 6, 26074.
- Tomé, D., Moughan, P., Burlingame, B., Millward, J., Pencharz, P., & Fuller, M. (2017). Evaluación de la calidad de las proteínas de la dieta en nutrición humana: consulta de expertos, 31 de marzo-2 de abril, 2011, Auckland, Nueva Zelanda.
- Do you know the Essential Amino Acids? Click here.
- We talk about the importance of the pH on the organism on this link.